Percutaneous Coronary Angioplasty is a therapeutic medical procedure that can increase blood flow through the coronary artery. It can sometimes be used as an alternative to coronary by-pass surgery. An elongated catheter having a deflated balloon at its distal end is guided through a patient's cardiovascular system to the coronary artery of the heart. The balloon is inflated to compress deposits that have accummulated along the inner walls of the coronary artery to widen the artery lumen and increase blood flow.
A known technique for positioning the balloon catheter uses an elongated guidewire that is inserted into the patient and routed through the cardiovascular system as guidewire progress is viewed on an x-ray imaging screen.
The path the guidewire follows as it is inserted is tortuous. The distal tip is flexible to avoid damaging inner walls of the blood vessels that the guidewire tip contacts along the tortuous path. The distal tip is often pre-bent to a desired configuration so that the guidewire can be inserted into the branching blood vessels along the path. When the tip is pre-bent the physician must be able to orient the tip so it can be pushed into these branching blood vessels.
Representative prior art patents that disclose flexible, elongated guidewires are U.S. Pat. No. 4,545,390 to Leary, U.S. Pat. No. 4,538,622 to Samson et al. and U.S. Pat. No. 3,906,938 to Fleischhacker. U.S. Pat. No. 4,846,186 to Box et al. is assigned to the assignee of the present application and is incorporated herein by reference.
One problem with currently available guidewires concerns the visibility of the guidewire. If the guidewire is fully opaque on a viewing screen, it can hinder viewing of post angioplasty angiograms used in studying the effects the angioplasty procedure had on the treated vessel. Guidewires that have only an opaque tip do not adequately depict the arterial path on the viewing monitor.
U.S. Pat. No. 4,922,924 to Gambale et al. concerns a guidewire for use with a catheter. The guidewire includes a coil assembly that is formed from a highly radiopaque coil and a non-radiopaque coil, arranged in bifilar arrangement to define a moderate radiopacity guidewire section.